AMS2485 and MIL-DTL-13924 are key specifications that define the requirements for black oxide coatings on ferrous alloys and steel. Used extensively in aerospace, defense, and industrial applications, these standards ensure that black oxide finishes provide reliable corrosion resistance, enhanced surface performance, and a uniform appearance.
Black oxide coatings have been used since the early 1900s, when workers immersed iron parts into vats of boiling lye at 285-300°F heated over open fires. Despite the risks of handling scalding solutions, the process became widespread, and by the 1930's, black oxide had gained commercial importance. In 1948, the Society of Automotive Engineers (SAE) introduced AMS2485 to standardize the process and establish testing requirements for high-quality coatings.
For decades, the specifications required parts to be treated in boiling aqueous alkali oxidizing baths, even as technological advancements showed that identical coatings could be achieved at much lower temperatures. In 2024, Birchwood Technologies collaborated with the SAE Council to modernize the AMS2485 standard. The updated specification, AMS2485-M, now recommends that time and temperature conditions follow the chemistry manufacturer's guidelines. This change ensures that various formulations can be used effectively while maintaining the required coating quality. By accommodating advancements in chemical processes and supporting innovation, the updated specification remains relevant and inclusive of diverse manufacturing practices.
This update to coating specifications marks a turning point for the black oxide industry, enabling a move away from hazardous boiling caustic baths toward safer, more user-friendly solutions. For over 20 years, Birchwood Technologies has recognized that Tru Temp delivers the same high-quality black oxide coating at just 200°F — and now, the rest of the industry knows it too!
Both specifications outline similar requirements, including:
While Tru Temp 2nd Gen is certifiable to all required standards, the operator performing the black oxide process must conduct regular testing and paperwork to officially certify to these standards.
The full AMS2485 specification must be purchased from SAE International.
MIL-DTL-13924 can be downloaded for free.
